This invention relates to an apparatus for opening and closing a rear door of a vehicle such as a dump truck.
Hitherto, several apparatus for opening and closing a rear door of a vehicle have been already proposed. For example, the device disclosed in the Utility Model Publication No. 1783/87 employs an arrangement in which a hydraulic cylinder for opening and closing a rear door is used to open the rear door in a state horizontal relative to the floor surface of the bed. Further, the invention disclosed in the Patent Application No. 205483/89 which was previously filed by the same applicant as the applicant of this invention employs an arrangement comprising a bent link connected to the lower end portion of the rear door through a turn buckle and a receiving metal fitting pivotally affixed on the frame at a lower part of the bed so as to be able to support the free end of the bent link, thus to open the rear door in a state horizontal relative to the floor surface of the bed in a manner similar to that in the above-mentioned embodiment.
However, since these embodiments are both constituted so as to open the rear door in a backward direction of the bed, when letting a load down, the load slides on the inner wall surface of the rear door and falls down therefrom, so the rear door is injured and a weight of the load is directly or indirectly applied to the rear door or respective members, giving rise to a problem of lowered durability. Further, when closing the rear door, such a way or manner is taken to force or thrust up the rear door. This requires a considerably large force, resulting in the drawback that the hydraulic cylinder must be large-sized, and the like.